1. The Field of the Invention
The present invention generally relates to the field of fiber optic couplers and, more specifically, to a three-piece receptacle assembly for joining to a ferrule containing an optical component or sub-assembly.
2. The Relevant Technology
Fiber optic technologies are increasingly used for transmitting voice and data signals. As a transmission medium, fiber optics provide a number of advantages over traditional electrical communication techniques. For example, light signals allow for extremely high transmission rates and very high bandwidth capabilities. Light signals also can be transmitted over greater distances without the signal loss typically associated with electrical signals on copper wire. These light signals are transmitted over optical waveguides, such as the optical fibers found in fiber optic cable.
Ferrule-type plug/receptacle optical connectors are typically used to position two optical waveguides, such as optical fibers, so that light can propagate between the two waveguides. Additionally, ferrule-type plug/receptacle optical connectors can be used to optically couple a waveguide to an optical component or subassembly. In this latter implementation, a ferrule-type plug at the end of an optical fiber is configured for insertion into a sleeve of a correspondingly configured receptacle of the component or subassembly. When coupled together, the sleeve fixes the position of the optical fiber end within the receptacle so as to optically couple the fiber with the component of subassembly such as, a transmitter optical sub-assembly (TOSA), a receiver optical sub-assembly (ROSA), for example. The receptacle sleeve is typically inserted into a base that is fixed to a housing of the TOSA/ROSA. This sleeve/base combination is typically referred to as a receptacle assembly. The ferrule of the plug and sleeve of the receptacle are manufactured to specific tolerances to ensure a proper friction fit between them, which allows the ferrule to be repeatedly removed and reconnected to the sleeve, while assuring proper alignment of the optical path.
The inner sleeve diameter of a receptacle assembly for Single Mode applications needs to be tightly controlled to yield sufficient “wiggle” performance of the TOSA and/or ROSA. During a wiggle test, a fiber cable is inserted into the TOSA and/or ROSA and a side load is applied to the fiber cable, which can result in movement of the ferrule at the tip of the optical connector plug within the receptacle assembly sleeve. This movement typically occurs partially as a result of a small gap between the receptacle assembly sleeve and the ferrule of the connector plug. This movement results in an undesirable change of coupled power into the fiber cable, which can substantially degrade transfer of optical signals between the connected elements and therefore needs to be controlled.
In some applications, one attempt at improving wiggle performance of the TOSA and/or ROSA has been to require tight manufacturing tolerances for the receptacle assembly in terms of sleeve diameter and roundness. Such tight manufacturing tolerances help to minimize the movement of the ferrule and can be achieved by manufacturing processes known in the art.
To meet these tight manufacturing specifications in an economic manner, the receptacle assembly sleeve generally must be machined to its final tight manufacturing tolerances before being assembled with the receptacle assembly base. The assembly process, however, usually introduces deformation of the receptacle assembly sleeve. Positive deformation, which occurs when the diameter of the sleeve grows, often results in poor wiggle performance, thus negating the advantages of having the tight manufacturing tolerances for the receptacle assembly sleeves. Negative deformation, which occurs when the diameter of the sleeve shrinks, results in a “hard plug”, as a ferrule connector sticks or cannot be fully inserted anymore. In both cases if there is too much of deformation, parts need to be sorted out resulting in yield hit and higher costs.
Unfortunately, as a partial result of the tight manufacturing processes involved as described above, assembly of the sleeve with the receptacle assembly base can be made more difficult. Among these difficulties is the possibility of deformation of the receptacle assembly sleeve upon assembly with the base. This in turn leads to poor wiggle performance or a hard plug, which negates the intended benefit of the tight manufacturing tolerances used for these components.